cc: Simplify Task and its derived classes.

cc/tiles/image_decode_controller.h

Index: cc/tiles/image_decode_controller.h
diff --git a/cc/tiles/image_decode_controller.h b/cc/tiles/image_decode_controller.h
index e6826624b0cc46c1fd536119d97f6f44bcdabae5..cfc1f51dab4af16c83201e5f13dc8203909cb354 100644
--- a/cc/tiles/image_decode_controller.h
+++ b/cc/tiles/image_decode_controller.h
@@ -11,7 +11,6 @@
 
 namespace cc {
 
-class ImageDecodeTask;
 class Task;
 
 // ImageDecodeController is responsible for generating decode tasks, decoding
@@ -19,11 +18,11 @@ class Task;
 // when requested.
 
 // ImageDecodeController is responsible for the following things:
-// 1. Given a DrawImage, it can return an ImageDecodeTask which when run will
-//    decode and cache the resulting image. If the image does not need a task to
-//    be decoded, then nullptr will be returned. The return value of the
-//    function indicates whether the image was or is going to be locked, so an
-//    unlock will be required.
+// 1. Given a DrawImage, it can return an Task which when run will decode and
+//    cache the resulting image. If the image does not need a task to be
+//    decoded, then nullptr will be returned. The return value of the function
+//    indicates whether the image was or is going to be locked, so an unlock
+//    will be required.
 // 2. Given a cache key and a DrawImage, it can decode the image and store it in
 //    the cache. Note that it is important that this function is only accessed
 //    via an image decode task.
@@ -36,7 +35,9 @@ class CC_EXPORT ImageDecodeController {
  public:
   virtual ~ImageDecodeController() {}
 
-  // Fill in an ImageDecodeTask which will decode the given image when run. In
+  // TODO(prashant.n): Update this comment properly to reflect upload and decode
+  // tasks.
+  // Fill in an Task which will decode the given image when run. In
   // case the image is already cached, fills in nullptr. Returns true if the
   // image needs to be unreffed when the caller is finished with it.
   //
@@ -44,7 +45,7 @@ class CC_EXPORT ImageDecodeController {
   // a raster task.
   virtual bool GetTaskForImageAndRef(const DrawImage& image,
                                      uint64_t prepare_tiles_id,
-                                     scoped_refptr<ImageDecodeTask>* task) = 0;
+                                     scoped_refptr<Task>* task) = 0;
   // Unrefs an image. When the tile is finished, this should be called for every
   // GetTaskForImageAndRef call that returned true.
   virtual void UnrefImage(const DrawImage& image) = 0;